Liquid crystal display device

ABSTRACT

A liquid crystal display device includes a thin film transistor substrate, a counter substrate that faces the thin film transistor substrate, a liquid crystal composition that is arranged between the thin film transistor substrate and the counter substrate, an oriented film that arranges orientation of the liquid crystal composition contacting with the thin film transistor substrate, a seal material that seals the liquid crystal composition between the two substrates, and a driver circuit. The driver circuit has a light transmission area that is formed inside of the driver circuit, and is higher in light transmittance than an area in which a non-transparent conductive film forming the driver circuit is formed, and a high sealing property area in which the seal material and an insulating film come into direct contact with each other between the light transmission area and an outer edge of the thin film transistor substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 13/677,349, which claims priority from Japaneseapplication JP2011-254094 filed on Nov. 21, 2011, the entire contents ofwhich are hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device.

2. Description of the Related Art

As an information communication terminal such as a computer and adisplay device such as a television, liquid crystal display devices havebeen widely used. The liquid crystal display device changes anorientation of a liquid crystal composition confined between two glasssubstrates according to a change in electric field, and controls thedegree of transmission of light that passes through the two glasssubstrates and the liquid crystal composition to display an image.

In the liquid crystal display device, there is a need to arrange adriver circuit for applying a voltage corresponding to a given tonevalue to respective pixels on a screen on the glass substrate or acircuit board connected to the glass substrate. There has been known thedriver circuit that is incorporated into an IC (integrated circuit)chip, and placed on the glass substrate. In recent years, it isdesirable to narrow an area outside a display area on the glasssubstrate (hereinafter referred to as “frame area”). Therefore, there isa case in which a thin film transistor is formed on the frame areawithout mounting the IC chip thereon, and the driver circuit is arrangeddirectly on the glass substrate without using the IC chip.

JP 2006-080472 A discloses a structure in which a parasitic capacity isreduced in an amorphous silicon thin film transistor arranged in theframe area.

In the liquid crystal display device having the frame area thusnarrowed, an oriented film that defines the orientation of the liquidcrystal composition may be formed on the driver circuit, and a seal withwhich a portion between the glass substrates is sealed may be formed onthe oriented film. In this case, when the adhesiveness of the sealformed on the oriented film is not sufficient, or the seal is notsufficiently cured, there is a risk that moisture penetrates inside of apanel to adversely affect the characteristic of the liquid crystalcomposition.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above-mentionedcircumstances, and therefore an object of the present invention is toprovide a display device that can seal the liquid crystal compositionwith high sealing property while realizing the narrowed frame area.

According to the present invention, there is provided a liquid crystaldisplay device, including a thin film transistor substrate on which athin film transistor is formed; a counter substrate that faces a surfaceof the thin film transistor substrate on which the thin film transistoris formed; a liquid crystal composition that is arranged between thethin film transistor substrate and the counter substrate; an orientedfilm that arranges orientation of the liquid crystal compositioncontacting with the thin film transistor substrate; a seal material thatsticks the thin film transistor substrate and the counter substratetogether, and seals the liquid crystal composition; and a driver circuitthat is formed outside of a display area of the thin film transistorsubstrate with the user of the thin film transistor, and outputs ascanning signal to scanning signal lines in the display area, in whichthe driver circuit has a light transmission area that is formed insideof the driver circuit, and is higher in light transmittance than an areain which a non-transparent conductive film forming the driver circuit isformed, and a high sealing property area in which the seal material andan insulating film come into direct contact with each other between thelight transmission area and an outer edge of the thin film transistorsubstrate, when viewed from a display direction.

Also, in the liquid crystal display device according to the presentinvention, in the driver circuit, a main transistor having a source or adrain connected directly or indirectly to the scanning signal line mayhave a plurality of pectinate channel areas in which a pectinate drainsignal line and a pectinate source signal line are alternating with eachother, the transistors formed by the plurality of pectinate channelareas may form circuits connected in parallel to each other, and thelight transmission area may be arranged between the plurality ofpectinate channel areas when viewed from the display direction.

Also, in the liquid crystal display device according to the presentinvention, the light transmission area may be surrounded by agate signalline of the main transistor in at least three ways, when viewed from thedisplay direction.

Also, in the liquid crystal display device according to the presentinvention, the light transmission area may be surrounded by at least oneof a source signal line and a drain signal line of the main transistorin at least three ways, when viewed from the display direction.

Also, in the liquid crystal display device according to the presentinvention, the plurality of pectinate channel areas may be formed byforming the main transistor into a crank shape as a whole.

Also, in the liquid crystal display device according to the presentinvention, the light transmission area may be surrounded by an electrodeforming a capacitor in the driver circuit in at least three ways, whenviewed from the display direction.

Also, in the liquid crystal display device according to the presentinvention, the oriented film may be stacked on the light transmissionarea.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a liquid crystal displaydevice according to a first embodiment of the present invention;

FIG. 2 is a front view illustrating a liquid crystal panel in FIG. 1;

FIG. 3 is an enlarged diagram illustrating an appearance of wiring in anarea A of a driver circuit in FIG. 2;

FIG. 4 is a circuit diagram illustrating a main transistor in FIG. 3;

FIG. 5 is a schematically cross-sectional view taken along a line V-V inFIG. 3;

FIG. 6 is a diagram illustrating a main transistor according to a firstmodified example of the first embodiment;

FIG. 7 is a diagram illustrating a main transistor according to a secondmodified example of the first embodiment;

FIG. 8 is a diagram illustrating a main transistor according to a thirdmodified example of the first embodiment;

FIG. 9 is a diagram illustrating a main transistor according to a fourthmodified example of the first embodiment;

FIG. 10 is an enlarged diagram illustrating an appearance of wiring inan area A of a driver circuit in FIG. 2 in the second embodiment;

FIG. 11 is a circuit diagram of a capacitor in FIG. 10; and

FIG. 12 is a schematically cross-sectional view taken along a lineXII-XII in FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a description will be given of a first embodiment and asecond embodiment of the present invention with reference to theaccompanying drawings. In the drawings, the same or equivalent elementsare denoted by identical reference numerals or symbols, and repetitivedescription will be omitted.

First Embodiment

FIG. 1 schematically illustrates a liquid crystal display device 100according to a first embodiment of the present invention. As illustratedin the figure, the liquid crystal display device 100 includes a liquidcrystal panel 200 fixed to be sandwiched between an upper frame 101 anda lower frame 102.

FIG. 2 illustrates a front view of the liquid crystal panel 200. Asillustrated in the figure, the liquid crystal panel 200 includes a thinfilm transistor substrate 201 having pixel circuits each using a thinfilm transistor formed in a display area 203, and a driver circuit 204using thin film transistors formed around the display area 203, a colorfilter substrate 202 having color filters of respective colors of R(red), G (green), and B (blue) formed for each of pixels, which is acounter substrate facing the thin film transistor substrate 201, aliquid crystal composition sealed between the thin film transistorsubstrate 201 and the color filter substrate 202, and a seal material205 for sealing the liquid crystal composition between the thin filmtransistor substrate 201 and the color filter substrate 202.

FIG. 3 is an enlarged diagram illustrating an appearance of wiring in anarea A of the driver circuit 204 in FIG. 2. In FIG. 3, there are shown ascanning signal line 305 that is connected to gates of pixel transistorsin the display area, a plurality of circuit drive signal lines 302 towhich a plurality of different clock signals are each supplied, a maintransistor 310 for supplying a clock signal of one circuit drive signalline 302 to the scanning signal line 305 at a given timing, a capacitor303, and a capacitor 304. As illustrated in the figure, the maintransistor 310 includes pectinate channel areas 311 and 312 havingpectinate source and drain electrodes engaged with each other. Betweenthe pectinate channel areas 311 and 312 are formed a light transmissionarea 313 in which a non-transparent conductive film is not formed, but alight transmittance is higher than that in an area where thenon-transparent conductive film is formed.

The circuit and wirings illustrated in FIG. 3 are exemplary, and acircuit used for the driver circuit 204 may be another circuit thatsupplies a pulse signal to the scanning signal line at a given timing.In this example, the light transmission area 313 is surrounded by a gatesignal line formed of a first conductive film 321 in four ways, and alsosurrounded by a source signal line and a drain signal line formed of asecond conductive film 323 in three ways.

FIG. 4 illustrates a circuit diagram of the main transistor 310. Asillustrated in the circuit diagram, the main transistor 310 isconfigured so that a first sub-transistor 331 formed by the pectinatechannel area 311 and a second sub-transistor 332 formed by the pectinatechannel area 312 are connected in parallel to each other. A gate, adrain, and a source of the first sub-transistor 331, and a gate, adrain, and a source of the second sub-transistor 332 are connected toone node 315, one pulse signal line 316, and one fixed signal line 317,respectively.

FIG. 5 is a schematically cross-sectional view taken along a line V-V inFIG. 3. FIG. 5 illustrates a cross-section of the main transistor 310and the capacitor 303 with the inclusion of the first conductive film321 which is an opaque metal film formed as a part of the thin filmtransistor substrate 201, a first insulating film 322, a semiconductorfilm 326, the second conductive film 323 which is an opaque metal film,a second insulating film 324, an oriented film 325 formed so as to bepoured from the display area 203 side, and the seal material 205 formedfor sealing the liquid crystal composition between the seal material 205and the color filter substrate 202. The liquid crystal composition andthe film on the color filter substrate 202 are omitted from the drawing.

As schematically illustrated in the figure, the first conductive film321, the first insulating film 322, the semiconductor film 326, thesecond conductive film 323, and the second insulating film 324 areformed in the stated order. Thereafter, the oriented film 325 formed soas to be poured from the display area 203 side is so stemmed as to beimpounded in a recess C of the light transmission area 313, and theoriented film 325 is not arranged in an area D. With this configuration,a high sealing property area 328 is formed in which the secondinsulating film 324 and the seal material 205 come into direct contactwith each other through no oriented film 325. As a result, theadhesiveness and the tightness of the seal material 205 can be improved,moisture can be prevented from penetrating inside of a liquid crystalpanel, and the characteristics of the liquid crystal composition can beenhanced.

Also, in an ultraviolet irradiation process for curing the seal material205, because ultraviolet rays transmit from the light transmission area313, the seal material 205 can be sufficiently cured, and moisture canbe prevented from penetrating inside of the liquid crystal panel causedby uncuring.

FIG. 6 schematically illustrates a main transistor 410 which is a firstmodified example of the main transistor 310 of the first embodiment. Asillustrated in the figure, in the main transistor 410, the lighttransmission area 313 is formed between pectinate channel areas 411 and412 as in the main transistor 310. However, the main transistor 410 isdifferent from the main transistor 310 in that a direction of extendingthe light transmission area 313 is perpendicular to a direction ofextending the pectinate source and drain. Even in this configuration,the main transistor 410 is configured so that a first sub-transistorformed by the pectinate channel area 411 and a second sub-transistorformed by the pectinate channel area 412 are connected in parallel toeach other. Also, the light transmission area 313 is surrounded by agate signal line formed of the first conductive film 321 in four ways,and surrounded by a source signal line and a drain signal line formed ofthe second conductive film 323 in three ways.

FIG. 7 schematically illustrates a main transistor 420 which is a secondmodified example of the main transistor 310 of the first embodiment. Asillustrated in the figure, the main transistor 420 is formed into acrank shape as a whole to form pectinate channel areas 421 and 422, andthe light transmission area 313 is formed between the pectinate channelareas 421 and 422. Thus, the main transistor 420 is formed into thecrank shape as a whole, as a result of which a boundary between the maintransistor and the adjacent main transistor is also formed into thecrank shape, and a progress of the oriented film poured into theconfiguration as illustrated in FIG. 7 is slowed, thereby making itdifficult to put the oriented film on an entire surface of the secondinsulating film. As a result, the second insulating film and the sealmaterial are liable to come into direct contact with each other. Even inthis configuration, the main transistor 420 is configured so that thefirst sub-transistor formed by the pectinate channel area 421 and thesecond sub-transistor formed by the pectinate channel area 422 areconnected in parallel to each other. Also, the light transmission area313 is surrounded by the gate signal line formed of the first conductivefilm 321 in four ways, and also surrounded by the source signal line andthe drain signal line formed of the second conductive film 323 in thethree directions.

FIG. 8 schematically illustrates a main transistor 430 which is a thirdmodified example of the main transistor 310 of the first embodiment. Asillustrated in the figure, as in the second modified example, the maintransistor 430 is formed into a crank shape as a whole to form pectinatechannel areas 431 and 432, and the light transmission area 313 is formedbetween the pectinate channel areas 431 and 432. In this example, thelight transmission area 313 is not arranged between the source line andthe drain linen as in the second modified example, but the source lineand the drain line approach one side, and the other side at which thesource line and the drain line are not present is set as the lighttransmission area 313 coupled to a boundary between the main transistorand the adjacent main transistor. With the above configuration, theoriented film 325 (refer to FIG. 5) poured into the boundary between therespective main transistors as indicated by an arrow in FIG. 8 canarrive at the light transmission area 313 without a need to exceed abarrier of height, and the oriented film 325 is liable to be accumulatedin the light transmission area 313. Even in this configuration, the maintransistor 430 is configured so that the first sub-transistor formed bythe pectinate channel area 431 and the second sub-transistor formed bythe pectinate channel area 432 are connected in parallel to each other.Also, the light transmission area 313 is surrounded by the gate signalline formed of the first conductive film 321 in the three ways, and alsosurrounded by the source signal line and the drain signal line formed ofthe second conductive film 323 in the three ways.

FIG. 9 schematically illustrates a main transistor 440 which is a fourthmodified example of the main transistor 310 of the first embodiment. Asillustrated in the figure, as in the third modified example, the maintransistor 440 is formed into a crank shape as a whole to form pectinatechannel areas 441 and 442, and the light transmission area 313 coupledto the boundary between the main transistor and the adjacent maintransistor is formed. Further, the main transistor 440 is different fromthe main transistor 310 in that the first conductive film 321 and thesemiconductor film 326 are separated by the pectinate channel areas 441and 442. With this configuration, the oriented film 325 (refer to FIG.5) is poured into the light transmission area 313 from two ways asindicated by an arrow in FIG. 9 so that the oriented film 325 is moreliable to be accumulated in the light transmission area 313. Even inthis configuration, the main transistor 440 is configured so that thefirst sub-transistor formed by the pectinate channel area 441 and thesecond sub-transistor formed by the pectinate channel area 442 areconnected in parallel to each other. Also, the light transmission area313 is surrounded by the source signal line and the drain signal lineformed of the second conductive film 323 in the three ways.

Even in the configurations illustrated in the above-mentioned first tofourth modified examples, as with the main transistor 310 in the firstembodiment, the oriented film is so stemmed as to be impounded in thelight transmission area 313, and a high sealing property area 328 inwhich the second insulating film and the seal material come into directcontact with each other through no oriented film is formed. As a result,the adhesiveness and the tightness of the seal material can be improved,moisture can be prevented from penetrating inside of the liquid crystalpanel, and the characteristics of the liquid crystal composition can beenhanced.

Also, in the ultraviolet irradiation process for curing the sealmaterial, because ultraviolet rays transmit from the light transmissionarea 313, the seal material can be sufficiently cured, and moisture canbe prevented from penetrating inside of the liquid crystal panel causedby uncuring.

Second Embodiment

A second embodiment of the present invention will be described. Aconfiguration of a display device according to the second embodiment isidentical with the configuration of the first embodiment illustrated inFIGS. 1 and 2, and therefore a repetitive description will be omitted.

FIG. 10 is an enlarged diagram illustrating an appearance of wiring inan area A of the driver circuit 204 in FIG. 2. In FIG. 10, as in FIG. 3of the first embodiment, there are shown a scanning signal line 505 thatis connected to gates of pixel transistors in the display area, aplurality of circuit drive signal lines 502 to which a plurality ofdifferent clock signals are each supplied, a main transistor 510 forsupplying a clock signal of one circuit drive signal line 502 to thescanning signal line 505 at a given timing, a capacitor 503, and acapacitor 504. As illustrated in the figure, inside of each of thecapacitor 503 and the capacitor 504 a non-transparent conductive film isnot formed, but a light transmission area 513 which is higher in thelight transmittance than that an area where the non-transparentconductive film is formed is formed. In this example, the lighttransmission area 513 is surrounded by electrodes of the capacitor 503or 504 in the four ways, but may be surrounded in the three ways, andopened in one way.

FIG. 11 is a circuit diagram of the capacitor 503 divided by the lighttransmission area 513. As illustrated in the circuit diagram, thecapacitor 503 is structured by a first sub-capacitor 511 and a secondsub-capacitor 512 which are divided by the light transmission area 513and connected in parallel to each other. Both ends of the firstsub-capacitor 511 and the second sub-capacitor 512 are connected to onescanning signal line 516 and one fixed signal line 517, respectively.

FIG. 12 is a schematically cross-sectional view taken along a lineXII-XII in FIG. 10. FIG. 12 illustrates a cross-section of thesub-capacitor 512, with the inclusion of the first conductive film 321which is an opaque metal film formed as a part of the thin filmtransistor substrate 201, the first insulating film 322, the secondconductive film 323 that is an opaque metal film, the second insulatingfilm 324, the oriented film 325 formed so as to be poured from thedisplay area 203 side, and the seal material 205 formed for sealing theliquid crystal composition between the thin film transistor substrate201 and the color filter substrate 202. The liquid crystal compositionand the film on the color filter substrate 202 are omitted from thedrawing.

As illustrated in the figure, the first conductive film 321, the firstinsulating film 322, the second conductive film 323, and the secondinsulating film 324 are formed in the stated order. Thereafter, theoriented film 325 formed so as to be poured from the display area 203side is so stemmed as to be impounded in a recess E of the lighttransmission area 513, and the oriented film 325 is not arranged in anarea F. With this configuration, a high sealing property area 528 isformed in which the second insulating film 324 and the seal material 205come into direct contact with each other through no oriented film 325.As a result, the adhesiveness and the tightness of the seal material 205can be improved, moisture can be prevented from penetrating inside of aliquid crystal panel, and the characteristics of the liquid crystalcomposition can be enhanced.

Also, in an ultraviolet irradiation process for curing the seal material205, because ultraviolet rays transmit from the light transmission area313, the seal material 205 can be sufficiently cured, and moisture canbe prevented from penetrating inside of the liquid crystal panel causedby uncuring.

The liquid crystal display device according to the above-mentionedembodiments can be applied to any one of an IPS (in-plane switching)system, a VA (vertically aligned) system, and a TN (twisted nematic)system although the system is not particularly designated.

While there have been described what are at present considered to becertain embodiments of the invention, it will be understood that variousmodifications may be made thereto, and it is intended that the appendedclaims cover all such modifications as fall within the true spirit andscope of the invention.

What is claimed is:
 1. A display device, comprising: a thin filmtransistor substrate on which a thin film transistor is formed; adisplay area on which a plurality of pixels are formed; and a drivercircuit that is formed outside of the display area, and includes a mainthin film transistor and a capacitor; wherein the main thin filmtransistor has a channel area and a light transmittance portion, thechannel area includes a semiconductor film, a comb-like source electrodeand a comb-like drain electrode engaged with each other on thesemiconductor film, and a gate electrode, the capacitor has a firstconductive film and a second conductive film opposite to the firstconductive film, the light transmittance portion is higher in lighttransmittance than the first conductive film or the second conductivefilm, and the light transmittance portion is formed in the channel area.2. The display device according to claim 1, wherein the channel area isdivided into a first channel area and second channel area, the lighttransmittance portion is provided between the first channel area andsecond channel area.
 3. The display device according to claim 2, whereinthe first and second channel area are formed into a crank shape as awhole.
 4. The display device according to claim 1, wherein the lighttransmission portion is surrounded by the gate electrode of the mainthin film transistor in at least three ways, when viewed from thedisplay direction.
 5. The display device according to claim 1, whereinthe light transmission portion is surrounded by at least one of thecomb-like source electrode and the comb-like drain electrode of the mainthin film transistor in at least three ways, when viewed from thedisplay direction.
 6. The display device according to claim 1, whereinthe light transmission portion is surrounded by the first and secondconductive film in at least three ways, when viewed from the displaydirection.
 7. A display device, comprising: a thin film transistorsubstrate on which a thin film transistor is formed; a display area onwhich a plurality of pixels are formed; and a driver circuit that isformed outside of the display area, and includes a main thin filmtransistor and a capacitor; wherein the main thin film transistor has achannel area and a light transmittance portion, the channel areaincludes a semiconductor film, a comb-like source electrode and acomb-like drain electrode engaged with each other on the semiconductorfilm, and a gate electrode, the capacitor has a first conductive filmand a second conductive film opposite to the first conductive film, thelight transmittance portion is higher in light transmittance than thefirst conductive film or the second conductive film, and the lighttransmittance portion is formed in the capacitor.
 8. The display deviceaccording to claim 7, wherein the capacitor is divided into a firstcapacitor and a second capacitor, the light transmittance portion isprovided between the first capacitor and the second capacitor.
 9. Thedisplay device according to claim 7, wherein the light transmissionportion is surrounded by the gate electrode of the main thin filmtransistor in at least three ways, when viewed from the displaydirection.
 10. The display device according to claim 7, wherein thelight transmission portion is surrounded by at least one of thecomb-like source electrode and the comb-like drain electrode of the mainthin film transistor in at least three ways, when viewed from thedisplay direction.
 11. The display device according to claim 7, whereinthe channel area has a first channel area and a second cannel area, thefirst and second channel area are formed into a crank shape as a whole.12. The display device according to claim 7, wherein the lighttransmission portion is surrounded by the first and second conductivefilm in at least three ways, when viewed from the display direction.